solar panels....Sold a lemon?

[Jim Gough]

What worries me is the fact the Shell don't seem to have the slightest idea about exported electricity. As it is I think I've managed to damage my inverter because the settings were that exporting wasn't allowed and ever since thusday when the batteries became fully charged the solar panels have not been generating hardly any power. The volts are there, but the power is fluctuating at very low levels. Looking at a graph of generation the output looks like a sawtooth. I'm really regretting having all this installed.

 

[Deleted account]

One member of staff isn’t shell.
is there a setting to stop exporting electric? If so, youd think the system would cope with that if that option is there.

also why would you stop the exporting electric. If your not using it why waste it?

 

[PEG]

Hi,i am almost certain that 11k spent on insulation,heat recovery/ventilation and more efficient appliances,would have yielded more joy

I am not sure what batteries/system you have,but what is the maximum load and duration of that load,which a fully charged battery can sustain? It was this question which steered me pal away from an 18 grand idea.....

I come across a lot of these installs,where it seems none of the installers,sellers,reps or homeowners,has a credible.understandable or matching description of its use or function.

 

[BeeJayEff]

Bit of a thread resurrection here .. that last comment about installers, sellers, reps failing to understand certainly rings true in my case. I'm in a similar position to the original poster. I have 13kWp of panels (10kWp after PVGIS calculations) with two Solis inverters and hadn't realised I would be limited to 3.68kW export (single phase). Installer took ages to get DNO approval via the G99 process.
Seems to me that installers talk about kWh, so they look at my typical usage - including my new electric car - and average that usage over the month/year/whatever, whereas of arguably more relevance is kW, Last week my panels were generating up to 8kW. As it happens, I was able to put 7kW of that into my car - but if I had been out in the car, what would have happened to that excess power ?
By the way, FiTs are no longer available. Now it's SEG (Smart Energy Generation) tariffs which all large suppliers are obliged to offer - not that their staff know about them (yes, looking at you, British Gas) ! I don't want to go to a cheap rate tariff such as Octopus Go, but will probably go for Octopus Agile for export and their standard tariff for import.
I don't (yet) have a battery - they seemed very expensive, but I shall reconsider as we go through the next year and see how much we export/import.

 

[Jim Gough]

Bit of a thread resurrection here .. that last comment about installers, sellers, reps failing to understand certainly rings true in my case. I'm in a similar position to the original poster. I have 13kWp of panels (10kWp after PVGIS calculations) with two Solis inverters and hadn't realised I would be limited to 3.68kW export (single phase). Installer took ages to get DNO approval via the G99 process.
Seems to me that installers talk about kWh, so they look at my typical usage - including my new electric car - and average that usage over the month/year/whatever, whereas of arguably more relevance is kW, Last week my panels were generating up to 8kW. As it happens, I was able to put 7kW of that into my car - but if I had been out in the car, what would have happened to that excess power ?
By the way, FiTs are no longer available. Now it's SEG (Smart Energy Generation) tariffs which all large suppliers are obliged to offer - not that their staff know about them (yes, looking at you, British Gas) ! I don't want to go to a cheap rate tariff such as Octopus Go, but will probably go for Octopus Agile for export and their standard tariff for import.
I don't (yet) have a battery - they seemed very expensive, but I shall reconsider as we go through the next year and see how much we export/import.

I've just bought another 9.6kw of batteries for mine as even in February on sunny days I was generating more than my batteries can store. I'm very interested about these SEG tarrifs as sofar the buggers have been getting my excess electricity for nowt. I've given up with shell energy they are without doubt the worst company I've ever had the misfortune of dealing with.

 

[BeeJayEff]

I've just bought another 9.6kw of batteries for mine as even in February on sunny days I was generating more than my batteries can store. I'm very interested about these SEG tarrifs as sofar the buggers have been getting my excess electricity for nowt. I've given up with shell energy they are without doubt the worst company I've ever had the misfortune of dealing with.

How do you judge what size battery/ies to go for ? My installers (in whom I have little confidence) tell me that the inverters dissipate any excess power in the form of heat, but I can see no way that the inverters know how much power is being imported via the main CU ... but are you saying that all excess power is exported but it's only 3.68kW that you can get paid for (if you're on single phase) ?

 

[Jim Gough]

How do you judge what size battery/ies to go for ? My installers (in whom I have little confidence) tell me that the inverters dissipate any excess power in the form of heat, but I can see no way that the inverters know how much power is being imported via the main CU ... but are you saying that all excess power is exported but it's only 3.68kW that you can get paid for (if you're on single phase) ?

I use approx 10kwh a day and had 9.6kwh of batteries which if its sunny every day (hahaha!!!) lasts nicely from one day to the next, but it's rarely sunny every day and after about 3 hours of sunshine my batteries are full and excess power goes to the grid. No idea what your installer is talking about the inverter dissipating heat. Mine is not even slightly warm to touch. I think the 3.68kW reference was to how much you could export when the government scheme was running which ended in 2019. (just shows how much the tory ----ers care about the environment....)

 

[Simon47]

How do you judge what size battery/ies to go for ?

You wet a finger, stick in in the air, then reach down your pants and pull a figure out of your backside
More seriously, there isn't a magic formula. It's a tradeoff.
On the one hand, the more capacity you have, the better you can take advantage of sunny days and store the energy for less sunny days. With a small battery, as noted above, on a really sunny day you'll fill them quickly and then not get the benefit of storing your lecky for later - you'll have to either back off the system or export the excess for a pittance, then buy in when you need it later. With a huge battery, you'll possibly need several really good days to fully charge them and thus get the benefit of keeping all the energy you capture.
The flip side is that bigger batteries cost more, take up more space, and will lose more to self discharge.
I guess you can try and figure out your average usage, how much you could produce from the panels on a good day, and size the batteries to deal with that. But I suspect there's a lot of guesswork involved for that.
Another consideration is that with a small battery you will be working it harder - deeper discharge, higher charge/discharge rates. That's going to age it faster than the same work going into a larger battery. Note that for EVs, they are still advising that for maximum battery life you should go below 30% on discharge or above 80-90% on charge - it tends to be the ends of the charge (the deep discharge, and full charge) that age the cells most.

My installers (in whom I have little confidence) tell me that the inverters dissipate any excess power in the form of heat, but I can see no way that the inverters know how much power is being imported via the main CU ... but are you saying that all excess power is exported but it's only 3.68kW that you can get paid for (if you're on single phase) ?

Your installer is a clueless fu**wit - as are many.
When the inverter reaches its limit, then it'll convert that much and no more - the panel DC voltage will rise higher than it would be with a more powerful converter and the same amount of sunlight.